This invention relates generally to automatic gain control circuits and to systems employing such circuits. In one particular aspect, the invention relates to a linear digital gain control circuit in a data communication receiver and a method of automatic gain control which prevents signal distortion, amplifier saturation and inter-modulation of signals presented to the receiver.
In another aspect, the invention relates to a linear digital gain control circuit and receiver for use in frequency multiplex communication systems of the type wherein the amplitude of transmitted data signals of several frequencies varying over a wide range of signal levels are digitally controlled to substantially eliminate frequency intermodulation products of the several frequencies from interfering with other ones of the frequencies to allow the data signals to be selectively received by one or more receiver circuits tuned to respective ones of the several frequencies.